title: Ion-exchange resins in the isolation of nitrogen compounds from petroleum residues.
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry; D007475:Ion Exchange Resins; D017672:Nitrogen Compounds / Q000302:isolation & purification*; D010578:Petroleum / Q000032:analysis*
chemical_list: D007475:Ion Exchange Resins; D017672:Nitrogen Compounds; D010578:Petroleum